This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 16 |
| 6 | 88 |
| 7 | 625 |
| 8 | 5527 |
| 9 | 55760 |
| 10 | 640540 |
| 11 | 8329326 |
| 12 | 120212331 |
| 13 | 1905939913 |
| 14 | 32987637967 |
| 15 | 618591571085 |
| 16 | 12489644875037 |
| 17 | 270193806214360 |
| 18 | 6235154917414954 |
| 19 | 152875655211527878 |
| 20 | 3968729594485785289 |
| 21 | 108754865309750398187 |
| 22 | 3137052120203959610759 |